The invention relates to a digital signal receiver device comprising input means supplying output signals representative of the logic state of the digital signals applied to the input of the receiver device, a processing circuit and means for filtering strays.
The links between electronic equipment in disturbed industrial environments are often achieved by transmission lines which carry digital information in serial or parallel form. The lines may be in synchronous or asynchronous mode. For protection of these lines, it is state of the art to shield the links by using special cables whose shielding is connected to the general frame ground of the electrical installation or earthed. However, in some cases it happens that high energy signals reach the receiver. Clipping devices eliminating the voltage surges so as to protect the electronic components, and analog filters, achieved with RC or LR cells, enable the undesirable effects of strays to be reduced. These disturbed links are located for example near high-current or high-voltage breaking devices such as circuit breakers or switches.
Transmission lines in industrial environments are greatly affected by electromagnetic disturbances, and the strays which are superposed on the useful signals are very difficult to eliminate completely. Shielding of the connecting cables, protection by clipping of the voltage surges and analog filtering enable the level of electromagnetic susceptibility to be greatly increased. But for very high levels of disturbance, these means are insufficient and the signals bearing the information may present inacceptable defects.
The object of the invention is to achieve a digital filtering device enabling the strays present on the signals bearing the information to be eliminated.